* This post pertains to an assignment for my exercise science class. We were given five possible essay titles to prepare for, one of which would be given to us on the day of the test whereupon we were to write an appropriate essay in 50 minutes. These are my preparatory notes/research for this assignment.
They consist of partly written essays, bulletpoint notes and references to scientific literature. Some of the essays are more well researched than others, some not at all. The ‘limiting factors of maximal oxygen uptake’ question was the one which was chosen for my test. My essay received a C1. *
Article for a running magazine explaining the nutritional and hydration strategies a marathon runner could adopt in the week before and during a race to maximise performance.
- Normal Nutrition Compared to Athletes
Carb(50-75%), Fat(15-30%) Pro(10-15%). Athletes have much the same requirements, Carbs ~55% (non endurance), 60-70% (endurance).
Major difference is in energy consumption (kcal). Usual = Men/2300 ; Women/1600. Athletes need much more, marathon runners specifically –
The reason athletes require so much more energy is that they are using more calories for training and performance. Energy intake must equal or exceed energy output (both exercise and the needs of resting metabolism).
This then, satisfies the basic needs of a body undergoing the stress of intensive training and exertion. But maximising performance requires further strategy in terms of the exact diet that is consumed, as well as when it is consumed.
- Carbs and protein
For best performance, athletes must design a regimen which involves eating prior to, during and after an event (this also applies to fluid intake, as we will see later).
Carbohydrate loading is the process of varying usual exercise intensity in tandem with an increased intake of high carbohydrate meals such as pasta – MAXIMISE GYCOGEN STORED IN MUSCLES.
Only really beneficial in exercise exceeding 90 minutes. Solid food for endurance, liquid for short.
Should do less intense exercise and eat 70%CARBS 3 days prior to event. Practice is important for the GIT to be acclimated to this process.
Marathon runners often describe ‘hitting the wall’, wherein carb stores have been expended and the body switches to fat. This process attempts to compensate for this by having as great a store as possible. Aim to defer hitting the wall.
- During exercise
It is important to have a carb intake during exercise: elevates blood glucose, can be used in lieu of muscle glycogen store.
Typically increase time to exhaustion by up to 60 minutes. Should eat at intervals across period of exercise, not just when tired.
- Post Exercise
Carbohydrates should be eaten in the 2 hours after exercise (~100g), and then consistently over the following 24 hour period.
This is beneficial as it replaces the muscle glycogen stores lost during exercise. Food should be easily digestible.
- Fat & Protein
Protein supplements are often readily used by athletes, however the recommended intake (120g/day) is grossly overstated. The necessary amount of protein can be gained through diet.
Increasing the amount of fat in the diet will not improve performance (Wee et al, 1999). It is possible that the longer time necessary to digest fat may cause discomfort and impact performance.
Athletes must attempt to replenish lost fluids, and replenish fluid across the race at regular intervals. Maintenance of hydration can be difficult as the body does not reliably relay the status of hydration through the sensation of thirst.
Marathon runners should drink 6ml/kg of body weight in fluid 20 minutes prior to start.
Proper hydration is necessary for thermoregulation via sweating, defers fatigue and discomfort from thirst.
Overconsumption of water is of serious concern, as it can lead to hyponatremia. Symptoms caused by excessive water retention and dilution of sodium content of blood.
This is part of the reason that isotonic sports drinks are favoured over water. These drinks replenish electrolytes which may be lost during exercise as well as carbohydrates. The content of these drinks has a similar concentration of salt and electrolytes as that of blood. This helps avoid water intoxication, as the blood will not be diluted.
Write an evidence based report on the concept of “live high, train low” to guide the Scottish Triathlon association in their decision.
- What is live high train low?
The training methodology in which athletes spend their time at a high altitude (that is, living defined as time not training) while descending to a lower altitude to go about their training as they normally would.
By training at a lower altitude, the HiLo program is thought to overcome the drawbacks of other altitude training regimes – namely that athletes cannot train as hard at altitude as at sea level thus reducing the benefit gained from training overall as well as athletes having less time to practice.
The aim of this period of high altitude life is to take advantage to the natural adaptions which the body will undergo in order to acclimate to the change in altitude. Namely increased levels of erythropoietin which in turn generates a greater number of red blood cells and leads to a resultant increase in VO2 max values for the athletes in question.
- Evidence for
Write an article for a running magazine explaining what factors limit maximal oxygen uptake and marathon performance in elite distance runners at sea level.
- What is VO2max? Relevance to runners.
Maximal oxygen uptake (VO2 max) is the maximum capacity of an individual’s body to transport and use oxygen during incremental exercise. Good quantitative measure of individual fitness.
During exercise the body must utilise fuels found in tissue at a greater rate than when resting. This process requires oxygen.
As work rate increases, oxygen uptake also increases up to a maximum value beyond which no more oxygen can be taken up, regardless of increasing exercise intensity.
Formally defined by Fick equation; VO2max = Q(CaO2 – CvO2) – ie CARDIAC OUTPUT (ART O2 – VENOUS O2)
VO2 = HR*SV (a-v O2 difference)
Typical elite distance runner would be in an interval of 70-90 ml per kg per minute.
Important to runners because VO2 max has a positive linear relationship with athletic performance. That is, a higher VO2 max will make for a shorter time.
- Pulmonary diffusing capacity**
This is a measure of how well the lungs transfer gas into and out of the blood. Therefore it will determine how fully haemoglobin proteins in red blood cells are saturated with oxygen.
In this case, untrained individuals actually have almost full (95%) haem saturation at sea level, while elite endurance athletes often undergo arterial O2 desaturation [AT MAXIMAL WORK].
This occurs because haemoglobin is naturally very capable of binding to O2 regardless of training.
Higher max cardiac output in elite athletes essentially gives the circulating blood less time in the pulmonary capillaries – leading to sub maximal O2 saturation.
- The Heart*
As we have seen in the previous discussion of pdifcap, a high cardiac output limits O2 sat. Other limits?
Heart rate is not actually a limiting factor here, bpm is actually lower for trained individuals. This is due to the fact that the body has adapted to daily exercise and said changes have altered the functionality of the heart.
This is known as athletic heart syndrome. Changes to the heart involve increasing the chamber size of the left ventricle and the muscle mass and wall thickness.
As a result, stroke volume (the amount of blood pumped by the ventricles per beat) is increased and this is in fact the main differentiating factor of VO2 max between trained and untrained as well as being the most significant limiting factor in athletes.
This higher SV means a greater rate of blood flow and a resultant increase in VO2max.
- Other factors
The carrying capacity* of oxygen in the blood is a limiting factor to some extent, as blood infusions and injections of EPO can both improve VO2max. These are illegal in competition however, and there is no natural way to improve O2 carrying capacity at sea level. 10% improvement can be observed.
The extraction of O2 from the blood by the muscle is highly efficient. There is no plausible method for increasing the O2 that is extracted and even if there was – there is little scope for improvement.
Muscle tissue mitochondria are likewise a very minor factor in VO2 max. It is considered to be the case that the ability of muscle to utilize oxygen exceeds the ability of the cardiorespiratory system to deliver oxygen.
More mitochondria do improve other aspects of athleticism; however the effect on VO2 max is negligible.
Basset & Howley, 1997, 2000.
Write an article for BASES newsletter explaining the effect of anxiety and arousal on an athletes sporting performance. Include brief advice on how to manipulate these levels.
Often the focus for athletes is physical fitness and practice; to prepare the body for exertion and the mind to make decisions based on experience while using technique to execute actions.
Frequently overlooked is the impact that an athletes cognitive state has on sporting performance. There will be a degree of variability between individuals in terms of optimal mental conditioning, however the techniques available to manipulate these states are applicable to all and can improve performance.
Anxiety is a neuro-physiological reaction to a stimulus. Anxiety is not a static state; rather it exists on a continuum between deep sleep and extreme excitement.
POS+ or NEG– emotions are associated.
As a physiological reaction, the state of arousal being experienced manifests through various bodily mechanisms. HR. BP. PALMAR SWEATING. RESP RATE. SKIN CONDUCTIVITY. EMG – can be interpreted.
Thus the strength of arousal can be quantified with some degree of certainty.
The optimal arousal for sporting performance would most likely exist an equal distance between the two extremes.
Arousal is important for regulating attentiveness, information processing, motivation and readiness to respond to stimuli. All of these factors are of obvious importance while playing any sport.
Anxiety is a subjective feeling of apprehension and heightened physiological arousal. A natural response to stimulus, though stimulus that will elicit anxiety not predictable. Usually response to unavoidable situations.
It is also Multidimensional – it is made up of both a COGNITIVE and SOMATIC component.
The cognitive component includes ideation over possible outcomes. That is, the athlete would form expectations over things which may go wrong during competition. This also includes behavioural changes brought about by anxiety, such as an unwillingness to participate as one normally would – usually due to worry over what may go wrong.
The somatic component is the physical response of the body due to anxiety. This includes changes in bpm, sweating, pallor, fatigue, inability to sleep, trembling, headaches etc.
Extreme cognitive and somatic responses due to anxiety can be detrimental to performance for many reasons. Lack of sleep and fatigue will impact training as well as on day performance. Changes in behaviour may mean a player is unable to play as they normally would and will avoid risk and any situation which could go wrong.
Anxiety increases and decreases in tandem with arousal, and like arousal, should be neither too high nor too low.
The consequences of inordinately high arousal and anxiety have already been described. It may seem logical that having no anxiety would be best however this is not the case. If we bear in mind that arousal mediates motivation and anxiety at a reasonable interval will perform a similar function, then it follows that no anxiety will mean that an athlete will be too carefree and generally unmotivated. The stakes will be too low as it were, the athlete will not be motivated to perform at their full potential.
Cog Anxiety steadily rises week preceding event, drops as event goes on.
Too little anxiety can be detrimental just as too much anxiety can be as well.
TECHNIQUES TO MANIPULATE
Lower: release breathing, self talk, meditation, preperformance routines,
Increase: music, self talk
Article for a health and fitness magazine explaining the evidence underpinning why it is beneficial to be physically active and how much activity adults should do.
It has been found that a sedentary lifestyle yields a greater risk of death in terms of all cause mortality as well as specifically increasing risk of CVD.
Physical activity will reduce the risk of all cause mortality, and significantly decrease the risk of death due to CVD.
Any amount of exercise greater than sedentary will yield benefit, stratified by time exercising and exercise intensity. 1000-1500Kcal/week is a minimum guideline, more benefit from more exercise.
Encompasses broad spectrum of conditions, the underlying cause being athleroslerosis , when artery walls thicken due to accumulation of fatty substances like cholesterol.
Numerous maladys: coronary heart disease, infarction, stroke, high bp,
Number of unmodifiable risk factors.
Modifiable risk factors include physical activity (stress by extension).
Good epidem evidence of fitness protecting from CVD. Limited by studies being OBSERVATIONAL not EXPERIMENTAL. No evidence of CAUSALITY merely CORRELATION.
Intervention studies show some good evidence of causality.
CHOLESTEROL. Those doing high amounts of HIGH INTENSITY exercise are shown to have more ‘good’ HDL cholesterol and less ‘bad’ LDL cholesterol.
Exercise typically improves psyche and level of stress, this presumably will act upon CVD.
BLOOD PRESSURE. Increases with age, 140/90 =HYPERTENSION. Continuous AEROBIC exercise is needed to reduce bp and retain this improvement. A greater reduction is observed in black and asian individuals (predisposed to high bp) than in whites.
Exercise intensity, BMI seem to have no effect on bp reduction.
DIABETES. Disorder of blood glucose regulation
Type II – tissue resistant to effect of insulin. 90% of cases.
Exercise 40 minutes per day increases INSULIN SENSITIVITY, addressing the root cause of type II diabetes.
- Health guidelines
UK chief medical officer recommends 30 minutes of moderate intensity physical activity 5 days per week. Based on evidence/ studies concluded exg expenditure 200Kcal/day = health benefit.
This is not an optimal amount of exercise. Set the bar reasonably low to encourage exercise, hope that people start at this level of moderately active and progress to being active. Needs to be achievable.
Some people will require more than this, closer to 45-60 minutes per day, especially if previously obese.
Does not need to vigorous necessarily, take into account overall energy expenditure of activity when considering health benefit.
Account for accumulative effect of total eng expenditure. Daily activities like walking to work factor in.
Preferably 75min vigorous activity per week. Twice weekly strength exercise.
It is not acceptable to cease exercise. Previous exercise does not protect from CVD in the future in the absence of exercise.
Intensity of exercise is important in the protection attained. Moderate intensity constitutes brisk walk (4-5mph).
BR Heart J, 1990
Pate et al, 1995
Hardman & Stensel, 2003